The problem I can see with your query is that your subtotal comes from VI but your first column comes from NF which is in the right part of a left outer join. You will end up with ALL items without nf.nro_nota being grouped into one.

I need to know the order in which your records appear. You can't give a running total without knowing the order in which the records should appear. Is there a date column, or an ID column somewhere?

This article will describe one method to parse a delimited string into a table of data.
Why would I do that you ask? Let's say that you need to pass multiple parameters into a stored procedure to search for. For our sake, we'll say that we wa…

This video shows how to remove a single email address from the Outlook 2010 Auto Suggestion memory.
NOTE: For Outlook 2016 and 2013 perform the exact same steps.
Open a new email: Click the New email button in Outlook.
Start typing the address: …

You have products, that come in variants and want to set different prices for them? Watch this micro tutorial that describes how to configure prices for Magento super attributes.
Assigning simple products to configurable: We assigned simple products…